Geography of suicide in Japan: spatial patterning and rural-urban differences

Temporal evolution of suicide by levels of rurality and deprivation among Japanese adults aged 20 years or over between 2009 and 2022

PURPOSE

Previous studies have reported that levels of rurality and deprivation are factors associated with suicide risk. Reports on the association between rurality, deprivation and suicide incidence during the COVID-19 pandemic are scarce. The study aims to investigate how suicide rates evolved in areas with different levels of rurality and deprivation among Japanese adults aged 20 years or older between 2009 and 2022.

METHODS

This study used population density in 2020 as an indicator of rurality and per capita prefectural income in 2019 as a proxy for deprivation in Japan's 47 prefectures. Joinpoint regression analysis was performed to analyze secular trends in suicide rates by rurality and deprivation.

RESULTS

Suicide rates for both men and women at different levels of rurality and deprivation remained roughly parallel during the research period. Suicide rates for men and women at all levels of rurality and deprivation were on a downward trend until around 2019, just before the onset of the pandemic. Following this, suicide rates in women showed a clear upward trend, while the trend in suicide rates for men also changed around 2019, with a slightly increasing or flat trend thereafter. Changes in suicide rates were greater among women and those aged 20-59 years.

CONCLUSIONS

In Japan, time trends in suicide rates for both men and women have changed before and after the pandemic, but levels of rurality and deprivation across the 47 prefectures do not appear to have contributed much to these changes.

Time-varying living arrangements and suicide death in the general population sample: 14-year causal survival analysis via pooled logistic regression

AIMS

While past research suggested that living arrangements are associated with suicide death, no study has examined the impact of sustained living arrangements and the change in living arrangements. Also, previous survival analysis studies only reported a single hazard ratio (HR), whereas the actual HR may change over time. We aimed to address these limitations using causal inference approaches.

METHODS

Multi-point data from a general Japanese population sample were used. Participants reported their living arrangements twice within a 5-year time interval. After that, suicide death, non-suicide death and all-cause mortality were evaluated over 14 years. We used inverse probability weighted pooled logistic regression and cumulative incidence curve, evaluating the association of time-varying living arrangements with suicide death. We also studied non-suicide death and all-cause mortality to contextualize the association. Missing data for covariates were handled using random forest imputation.

RESULTS

A total of 86,749 participants were analysed, with a mean age (standard deviation) of 51.7 (7.90) at baseline. Of these, 306 died by suicide during the 14-year follow-up. Persistently living alone was associated with an increased risk of suicide death (risk difference [RD]: 1.1%, 95% confidence interval [CI]: 0.3-2.5%; risk ratio [RR]: 4.00, 95% CI: 1.83-7.41), non-suicide death (RD: 7.8%, 95% CI: 5.2-10.5%; RR: 1.56, 95% CI: 1.38-1.74) and all-cause mortality (RD: 8.7%, 95% CI: 6.2-11.3%; RR: 1.60, 95% CI: 1.42-1.79) at the end of the follow-up. The cumulative incidence curve showed that these associations were consistent throughout the follow-up. Across all types of mortality, the increased risk was smaller for those who started to live with someone and those who transitioned to living alone. The results remained robust in sensitivity analyses.

CONCLUSIONS

Individuals who persistently live alone have an increased risk of suicide death as well as non-suicide death and all-cause mortality, whereas this impact is weaker for those who change their living arrangements.

Exploring risk factors and their differences on suicidal ideation and suicide attempts among depressed adolescents based on decision tree model

BACKGROUND

Suicide has been recognized as a major global public health issue. Depressed adolescents are more prone to experiencing it. We explore risk factors and their differences on suicidal ideation and suicide attempts to further enhance our understanding of suicidal behavior.

METHODS

2343 depressed adolescents aged 12-18 from 9 provinces/cities in China participated in this cross-sectional study. We utilized decision tree model, incorporating 32 factors encompassing participants' suicidal behavior. The feature importance of each factor was measured using Gini coefficients.

RESULTS

The decision tree model demonstrated a good fit with high accuracy (SI = 0.86, SA = 0.85 and F-Score (SI = 0.85, SA = 0.83). The predictive importance of each factor varied between groups with suicidal ideation and with suicide attempts. The most significant risk factor in both groups was depression (SI = 16.7 %, SA = 19.8 %). However, factors such as academic stress (SI = 7.2 %, SA = 1.6 %), hopelessness (SI = 9.1 %, SA = 5.0 %), and age (SI = 7.1 %, SA = 3.2 %) were more closely associated with suicidal ideation than suicide attempts. Factors related to the schooling status (SI = 3.5 %, SA = 10.1 %), total years of education (SI = 2.6 %, SA = 8.6 %), and loneliness (SI = 2.3 %, SA = 7.4 %) were relatively more important in the suicide attempt stage compared to suicidal ideation.

LIMITATIONS

The cross-sectional design limited the ability to capture changes in suicidal behavior among depressed adolescents over time. Possible bias may exist in the measurement of suicidal ideation.

CONCLUSION

The relative importance of each risk factor for suicidal ideation and attempted suicide varies. These findings provide further empirical evidence for understanding suicide behavior. Targeted treatment measures should be taken for different stages of suicide in clinical interventions.

Spatial, geographic, and demographic factors associated with adolescent and youth suicide: a systematic review study

Background

Suicide is a public health issue and a main cause of mortality among adolescents and the youth worldwide, particularly in developing countries.

Objectives

The present research is a systematic review aiming to investigate the spatial, geographical, and demographic factors related to suicide among adolescents and the youth.

Methods

In this systematic review, two researchers examined PsycINFO, Web of Science, Scopus, and PubMed databases on December 7th, 2022 with no time limits from the beginning of publication until 2022 to identify the primary studies on spatial and geographic analysis on adolescent and youth suicides. Once duplicate studies were identified and removed, the titles and abstracts of studies were examined and irrelevant studies were also removed. Finally, 22 studies were reviewed based on the inclusion criteria.

Results

Our findings show that suicide rates are generally higher among men, residents of rural and less densely populated regions, coastal and mountainous regions, natives, 15-29 age group, less privileged populations with social fragmentation, unemployed, divorced or lonely people, those who live in single parent families, people with mental health issues, and those with low levels of education.

Conclusions

Stronger evidence supports the effects of geographic and demographic variables on youth and adolescent suicide rates as compared with spatial variables. These findings suggest that policy makers take spatial and demographic factors into consideration when health systems allocate resources for suicide prevention, and that national policymakers integrate demographic and geographic variables into health service programs.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023430994.

Association of Suicidal Ideation With Physical Health Conditions, Mental Health Conditions, and Multimorbidity and the Modifying Role of Emotional Social Support: A Cross-Sectional Study in Japan

INTRODUCTION

It is unclear whether the risk of suicide differs among individuals with only physical health condition, those with only mental health conditions, and those with both types of conditions (multimorbidity) and how emotional social support modifies these associations. This study aimed to examine differences in the association of suicidal ideation with the presence of only physical health conditions, only mental health conditions, and multimorbidity and the modifying role of emotional social support in these associations.

METHODS

A cross-sectional survey was conducted between August and September 2023 in a Japanese rural town to collect data. The exposure variable was the health condition, and it was classified into 4 groups: disease-free, only physical health conditions, only mental health conditions, and multimorbidity. The outcome variable was suicidal ideation. The data collected were analyzed using multivariate logistic regression analysis and stratified analysis.

RESULTS

Suicidal ideation was found to have a significant positive association with the presence of only mental health conditions and multimorbidity. These associations remained unchanged in the absence of emotional social support. However, the odds ratio for the only mental health conditions group decreased in the presence of emotional social support, while the odds ratio for the multimorbidity group remained significantly higher.

CONCLUSIONS

Suicidal ideation is positively associated with the presence of only mental health conditions and multimorbidity, but emotional social support modifies only the association between suicidal ideation and the presence of only mental health conditions. These results suggest that it may be important to identify the type of social support one needs based on one's health condition to prevent suicide.

Associations between social fragmentation, socioeconomic deprivation and suicide risk across 1887 municipalities in Japan, 2009-2017: a spatial analysis using the Bayesian hierarchical model

OBJECTIVE

Previous studies have indicated that spatial variation in suicide mortality is associated with area-specific socioeconomic characteristics, such as socioeconomic deprivation and social fragmentation. However, most of these studies have been conducted in the West and findings from Asian countries are limited. This study aims to investigate associations between socioeconomic characteristics and suicide mortality rates across 1887 municipalities in Japan between 2009 and 2017. We also assessed these associations by gender and age group.

METHODS

Suicide data were obtained from the suicide statistics of the Ministry of Health, Labour and Welfare in Japan and included information on the number of suicides by gender, age and municipality location. Social fragmentation, socioeconomic deprivation and urbanicity were used as socioeconomic characteristics in this study and were created from survey data obtained from the 2010 census. Bayesian hierarchical models were used to examine associations between socioeconomic characteristics and suicide risk.

RESULTS

Suicide rates were significantly higher in municipalities with higher levels of deprivation, with a rate ratio of 1.13 (95% credible interval: 1.10 to 1.17) in the highest quartile compared with the lowest. Higher levels of urbanicity had significantly lower suicide rates, with a rate ratio of 0.79 (95% credible interval: 0.77 to 0.82) in the highest quartile compared with the lowest. However, associations between exposures and suicide varied considerably by gender and age. Among both men and women aged 0-39 years, fragmentation was significantly associated with suicide, with rate ratios of 1.07 and 1.15 for men and women, respectively, in the highest quartile compared with the lowest.

CONCLUSION

Suicide prevention in Japan should particularly focus on areas with high levels of deprivation or low levels of urbanicity. Furthermore, young Japanese people residing in the most fragmented municipalities were also at high risk of suicide, and appropriate measures need to be taken.

Quantitative Methods to Detect Suicide and Self-Harm Clusters: A Systematic Review

Suicide and self-harm clusters exist in various forms, including point, mass, and echo clusters. The early identification of clusters is important to mitigate contagion and allocate timely interventions. A systematic review was conducted to synthesize existing evidence of quantitative analyses of suicide and self-harm clusters. Electronic databases including Medline, Embase, Web of Science, and Scopus were searched from date of inception to December 2020 for studies that statistically analyzed the presence of suicide or self-harm clusters. Extracted data were narratively synthesized due to heterogeneity among the statistical methods applied. Of 7268 identified studies, 79 were eligible for narrative synthesis. Most studies quantitatively verified the presence of suicide and self-harm clusters based on the scale of the data and type of cluster. A Poisson-based scan statistical model was found to be effective in accurately detecting point and echo clusters. Mass clusters are typically detected by a time-series regression model, although limitations exist. Recently, the statistical analysis of suicide and self-harm clusters has progressed due to advances in quantitative methods and geospatial analytical techniques, most notably spatial scanning software. The application of such techniques to real-time surveillance data could effectively detect emerging clusters and provide timely intervention.

Inequalities of Suicide Mortality across Urban and Rural Areas: A Literature Review

Suicide mortality is a major contributor to premature death, with geographic variation in suicide rates. Why suicide rates differ across urban and rural areas has not yet been fully established. We conducted a literature review describing the urban-rural disparities in suicide mortality. Articles were searched in five databases (EMBASE, PubMed, PsychINFO, Scopus, and Web of Science) from inception till 26 May 2021. Eligible studies were narratively analyzed in terms of the urban-rural disparities in suicides, different suicide methods, and suicide trends over time. In total, 24 articles were included in our review. Most studies were ecological and cross-sectional evidence tentatively suggests higher suicide rates in rural than in urban areas. Men were more at risk by rurality than women, but suicide is in general more prevalent among men. No obvious urban-rural pattern emerged regarding suicide means or urban-rural changes over time. Potential suicidogenic explanations include social isolation, easier access to lethal means, stigmatization toward people with mental health problems, and reduced supply of mental health services. For research progress, we urge, first, individual-level cohort and case-control studies in different sociocultural settings. Second, both rurality and urbanicity are multifaceted concepts that are inadequately captured by oversimplified typologies and require detailed assessments of the sociophysical residential environment.

Differences in depressive symptoms by rurality in Japan: a cross-sectional multilevel study using different aggregation units of municipalities and neighborhoods (JAGES)

Background

Rurality can reflect many aspects of the community, including community characteristics that may be associated with mental health. In this study, we focused on geographical units to address multiple layers of a rural environment. By evaluating rurality at both the municipality and neighborhood (i.e., a smaller unit within a municipality) levels in Japan, we aimed to elucidate the relationship between depression and rurality. To explore the mechanisms linking rurality and depression, we examined how the association between rurality and depression can be explained by community social capital according to geographical units.

Methods

We used cross-sectional data from the 2016 wave of the Japan Gerontological Evaluation Study involving 144,822 respondents aged 65 years or older residing in 937 neighborhoods across 39 municipalities. The population density quintile for municipality-level rurality and the quintile for the time required to reach densely inhabited districts for neighborhood-level rurality were used. We calculated the prevalence ratios of depressive symptoms by gender using a three-level (individual, neighborhood, and municipality) Poisson regression. Community social capital was assessed using three components: civic participation, social cohesion, and reciprocity.

Results

The prevalence of depressive symptoms was higher in municipalities with lower population density than those with the highest population density; the ratios were 1.22 (95% confidence intervals: 1.15, 1.30) for men and 1.22 (1.13, 1.31) for women. In contrast, when evaluating rurality at the neighborhood level, the prevalence of depressive symptoms was 0.9 times lower for men in rural areas; no such association was observed for women. In rural municipalities, community civic participation was associated with an increased risk of depressive symptoms. In rural neighborhoods, community social cohesion and reciprocity were linked to a lower risk of depressive symptoms.

Conclusions

The association between rurality and depression varied according to geographical unit. In rural municipalities, the risk of depression may be higher for both men and women, and the presence of an environment conducive to civic participation may contribute to a higher risk of depression, as observed in this study. The risk of depression in men may be lower in rural neighborhoods in Japan, which may be related to high social cohesion and reciprocity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12942-021-00296-8.